Let’s get back into HTTP. It’s a client-server protocol that specifies how Web clients request Web pages from Web servers and how Web servers send them.

Remember the following diagram from the lesson on Network Application Architectures? Well, it was actually outlining HTTP in general.

The orange arrow represents an HTTP request

The blue arrow represents an HTTP response

Clients obtain content (such as videos) and/or services (such as an online calculator) from servers.

Clients obtain content (such as videos) and/or services (such as an online calculator) from servers.

The first message is called an HTTP request and the second one an HTTP response. There’s a whole class of protocols that are considered request-response protocols. HTTP is one of them. We will look in more detail at the HTTP request message in the next lesson and response after that!

Note that HTTP is a stateless protocol: servers do not store any information about clients by default. So if a client requests the same object multiple times in a row, the server would send it and would not know that the same client is requesting the same object repeatedly.